Melting-pot heater for type and similar machines.



w. D. LUDWICKl MELTlNG POT HEATER FOR TYPE AND SIMILAR MACHINES.

APPLICATION FILED FEB. 11.1916.

1 1 97,042 v Pat ented Sept. 5, 1916.

W. D. LUDWICK.

MELTING POT HEATER FOR TYPE AND SIMILAR MACHINES.

APPLICATION mu) FEB. I7. 916.

1 ,1 97,042 Patented Sept. 5, 1916.

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MELTING POT HEATER FOR TYPE AND SIMILAR MACHINES.

APPLICATION FIL ED FEB. 17. 1916.

1,197,042. Patented Sept. 5,1916.

5 SHEETS-SHEET 3.

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W. D. LUDWICK.

MELTING POT HEATER FOR TYPE AND SIMILAR MACHINES.

APPLICATION FILED FEB-17,1916.

1,1 97,042. Patented Sept. 5, 1916.

5 SHEETS-SHEET 4.

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W. D. LUDWICK.

MELTING POT HEATER FOR TYPE AND SIMILAR MACHINES.-

APPLICATIQN FILED FEB. 11. 1916.

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WAYNE DOUGLAS LUDWICK, OF TACOMA, WASHINGTON.

MELTINGr-POT HEATER FOR TYPE AND SIMILAR MACHINES.

Specification of Letters Patent.

Patented Sept. 5, 1916.

Application filed February 17, 1916. Serial No. 78,930.

residing at Tacoma, in the county of Pierce and State of Washington, have invented certain new and useful Improvements in Melting-Pot Heaters for Type and Similar Machines; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification.

Inthe melting of type metal for casting type in the well known linotype machine, as well as in machines for melting the .more

fusible metals for other purposes, difficultyhas been encountered in arranging the melting pot so as to secure effective results without introducing elements of inconvenience or expense. In so far as practical commercial operations are concerned, it has, prior to the advent of the present invention, been almost the universal practice to employ gas burners for heating the melting pot, althou h the use of electrical heating means has been proposed, but, as a commercial proposition, has not eventuated probably because of difficulties which it is the object of the present invention to overcome. Among these difficulties may be mentioned the fact that the use of resistance coils, as in prior proposed practice, requires that the coils shall be located in the melting pot, in order to obtain economical results and failure, of the coils results in the congealing of the metal around the same, rendering them inaccessible and consequently extremely difficult to repair.

One of the principal objects of the present invention is'to provide a heater in which the heat is generated in the walls of the melting pot itself, due to the action of exterior and therefore readily accessible coils, said coils acting, not by resistance to the flow. of the electric current, but by the creation of hysteretic conditions in the melting pot walls, whereby the heat is generated at the point where the greatest economy will result.

A further object of the invention is to provide a melting pot in which the magnetic losses due to eddy currents and hysteresis will be confined to the melting pot itself with little or no loss by reason of external losses in the magnetic or electric circuit.

A further object of the invention is to provide a melting pot having a discharge duct, the temperature of which may be raised to'prevent the metal from cooling therein, or if desired, to increase the temperature of the metal immediately prior to its discharge, such heating being effected by induction and hysteresis in the walls forming the discharge duct at a point removed from the heater for the melting pot itself.

The invention consists in certain novel details of construction and combinations and arrangements of parts, all as will be hereinafter described and pointed out par ticularly in the appended claims.

Referring to the accompanying drawings, Figure 1 is a side elevation of certain of the working parts of an ordinary linotype ma chine in which the heater and melting pot of the present invention are incorporated. Fig. 2 is an enlarged side elevation of a portion of the mouth piece of the discharge duct shown in Fig. 1. Fig. 8 is a side elevation of the melting pot and heaters with the casing removed. Fig. %l is a top plan view of the melting pot heaters and casing, but with the cover of the casing removed. Fig. 5 is a sectional elevation in a plane indicated by the line 55 in Fig. 4. Fig. 6 is a section in a horizontal plane indicated by the line 66 in Fig. 5. Fig. 7 is a sectional elevation in a plane indicated by the line 77 of Fig. 5. Fig. 8 is a fragmentary sectional elevation in a plane indicated by the line 8-8 in Fig. 4. Fig. 9 is an elevation looking into the delivery or discharge mouth piece with a portion in section. Fig. 10 is a section in a broken plane indicated by the line 10-10 in Fig. 5.

Like reference characters in the several figures indicate the same parts.

In the conventional illustration of the mechanism for operating the melting pot and pump of a linotype machine shown in Fig. 1 of the accompanying drawings, an ordinary intermittently rotating mold wheel is indicated at 63, being carried on a hub or support 64- in front of the discharge duct or mouth piece ofothe melting pot. The casing of the melting pot indicated at 11 is mounted on a supporting arm 42 pivoted to the fixed frame 48 and its movement toward and from the mold wheel and the movements of the pump are controlled by cams 50 and 4A journaled at 45 in the fixed frame and driven from the power shaft of the machine.

The cam 50 cooperates with a roller 51 on a movable leg 52 pivoted at 53 to a bracket on the casing 11, and at its lower end supported by a spring (31 positioned by projection 62 on the fixed frame and hearing at its upper end against the collar on the supporting leg or standard 52. Intermediate the lower portion of the casing 11 and standard 52 is a pivoted rod 56 slotted at 57 for the reception of a pin 58 on the leg or standard 52 and surrounded by compression spring 59.

The pump plunger rod 21 is pivotally connected at its upper end 49 to the forward arm of a bell crank lever 7 pivoted at 48 on a fixed portion of the frame as and earrying a roller 4&6 for cooperation with the cam 4L4. The operation of these parts of the structure is similar to the operation of corresponding parts in the well known commercial machine being designed to effect a movement of the melting pot toward and from the mold wheel so as to seat the discharge nozzle 18 against the rear face of the mold, and when it is so seated, operate the pump to discharge metal from the melting pot into the mold for the formation of the type or casting.

In accordance with the present invention, the casing 11 serves as the inclosing means and support for a removable melting pot and discharge duct with its nozzle, and also as the inclosing means for the coils which act to produce the heat in the melting pot itself and in its discharge duct, the object of this particular arrangement being to facilitate the ready insertion or removal of the melting pot without disturbing any of the mechanical parts for operating the same, but in such wise that the registry of the nozzle with the mold wheel may be accurately effected. when a new melting pot is substituted. To the above ends, the melting pot 12 is formed with a lip or shoulder 41 adapted to seat on the casing near the rear upper edge thereof, as shown in Figs. f and 5,. and the discharge duct portion of the melting pot is formed with seats for the inner ends of screws 10, best seen in Figs. 1, 41, 9 and 10, mounted in the casing and adapted to permit of a slight lateral adjustment of the nozzle, whereby its accurate seating against the mold may be insured.

When the melting pot is located in position within the casing, the latter is closed by a cover 11, thus retaining the heat, and thus increasing the e'lliciency of the heater.

The melting pot 12, together with the forwardly extending portion 30 thereof through which the discharge duct 16 is formed, is composed of a magnetizable metal having a high hysteretic factor, preferably cast iron of a character which will resist change in its magnetic condition and permit the formation of eddy currents. The

body of the melting pot is formed with a downwardly extending and preferably substantially cylindrical well-like portion, in which there is formed a pump cylinder 13 communicating at the bottom with the discharge du ct 16 through a bottom passage 15. The lower portion of the walls of the pump cylinder join the exterior and bottom walls of the melting pot and the upper portions of the walls of the cylinder are preferably connected with the upper portions of the melting pot well by rib-like extensions 22 which complete a branch of the magnetic circuit from bottom to top of the well in the melting pot. The bottom of the melting pot is formed with a thickening portion 12 primarily for a purpose to be presently explained, and extending downwardly through this portion of the melting pot are passages 73 leading from the well 1% around the pump cylinder and to the bottom of the pump cylinder itself to facilitate drainage and cleaning of the pump well, such passages being normally closed by a plug, as will be readily understood. The pump piston 19 is pivotally connected with the connecting rod 21, at 20, as is usual in this class of apparatus.

Surrounding the cylindrical well of the melting pot is a relatively large coil preferably formed as a unit so that it may be removed or replaced without difficulty and for this purpose the coil indicated at 23 is usually inclosed by a covering of insulating material as is common with exciting coils of this character. The coil itself is preferably formed in sections so that one or more of the sections may be used as desired, and these sections may have a common return 67. Each has its leading in wire indicated at 65, 6G and 68, respectively. The melting pot forms the core of the coil, and the magnetic circuit is completed from opposite ends of the coil through paths which are designed to reduce as far as pos sible magnetic resistance, hysteresis or the Foucault current in the return circuit. To accomplish this end, the return circuit is formed by laminated magnetizable metal sections 24 preferably each of substantially L-shape and beveled at their upper ends to seat firmly beneath the undercut lower portions of brackets 12', formed on the exterior wall of the melting pot near the top. At their lower ends they seat squarely against the bottom 12 at the lower end of the melting pot. A number of these laminated sections is designed to form a complete magnetic return circuit practically without magnetic resistance, and in practice it has been found that four sections are sufficient for the purpose, as shown clearly in Fig. 6 of the accompanying drawings. The magnetic return sections 24 are clamped firmly in place and held in intimate contact with the melting pot by a cap member 25 fastened securely to the bottom 12 of the melting pot by a central screw 26 and to provide for individual adjustment the cap piece 25 is provided with wedge-like filler pieces 28 for cotiperation with inclined faces 27 on the sections 24, such wedge-like filler pieces being individually adjusted by set screws 29, as shown in the detail view Fig. 8. With this arrangement each of the laminated sections may be seated firmly and accurately so as to close the gap at their points of contact with the melting pot to reduce as far as possible magnetic resistance at these points, thereby contributing to the securing of a higher power factor.

The portion of the magnetizable metal forming the discharge duct is preferably made elliptical or cylindrical in proximity to the mouth piece 17 as indicated at 80 in Figs. 5 and 7, and this portion is surrounded by a coil 31 preferably also composed of three or more sections with terminals indicated at 69, and 72 and a return connection at 71. This portion of the discharge duct is of greater cross sectional area than necessary for the formation of the duct itself (which latter is usually of elongated form in cross section as shown at 16 in Fig. 7) and constitutes the core in which the heating effect, due to hysteretic and Foucault action is set up. The return of the magnetic circuit is formed by laminated sections 33 which in construction are very similar to the laminated sections forming thereturn of the magnetic circuit of the melting pot. As shown in Figs. 7 and 10, it will be noted that each of the laminated sections 33 is of substantially L-shape and contacts at one end with the exterior wall of the duct at the points indicated at 34, while the opposite ends are inclined or beveled and contact with the inclined surfaces 35 of the mouth piece 17. Clamping screws 37 are provided for urging the ends of the laminated sections into intimate contact with the mouth piece, and at the same time these inclined faces tend to force the laminated sections rearwardly and into contact with the inclined brackets 36 on the discharge duct. The inclines of the bracket 36 tend to force the laminated sections into contact with the wall of the discharge duct, and consequently both ends of the laminated sections are held firmly with a single adjustable connection at one end, just as is the case with the laminated sections forming the return circuit of the melting pot. While the mouth piece 17 may be formed integral with the cylindrical portion of the discharge duct, yet for convenience in manufacture and assembly, it is preferred that these two parts be made separately and dove-tailed together, as shown in Fig. 10.

In order to distribute the heating effect of the coil so that the mouth piece 17 will be brought up to the desired temperature without an excess of temperature in the portion of the discharge duct within the coil 31, a laminated section 32 is preferably introduced in the body of the duct extending through the coil. With this construction the heating effect becomes more marked in the mouth piece 17, a result which is desirable, inasmuch as the mouth piece is of large surface area and tends to cool rapidly. In this connection it may be noted that the laminated return circuit sections 83 contact at their forward ends with the laterally extended portions of the mouth piece, and consequently the heating effect will be distributed in such wise that the molten metal is kept at a proper temperature until it issues through the openings in the nozzle 18.

The operation of the heating portion of the apparatus will be readily understood by those skilled in the art inasmuch as when an alternating current is caused to flow in V the coils the magnetism induced thereby in the magnetic circuit will cause the very rapid heating of the hysteretic portion of well in the metal which is to be or has been liquefied, through the overcoming of the ohmic resistance therein.

The provision of sectional coils is important inasmuch as it is desirable in starting the heating operation to utilize more or less of the turns, but after the metal has been liquefied it requires less heat to maintain this condition and additional turns may be cut out of action. Should it be desired to leave the machine out of operation, but with the metal maintained at a liquid temperature therein, it will be necessary to utilize only one of the sections of the coil, thereby increasing the resistance and decreasing the flow of current. In so far as the heating of the exit duct and mouth piece is concerned, after these parts are brought up to the desired temperature,they may be maintained at that temperature, with the utilization of but a fraction of the current necessary to initially heat them.

What is claimed is 1. The combination with a melting pot having a well formed of magnetizable metal, of an electric conductor surrounding said well in the formof a coil and a return magnetic circuit in contact with the melting pot above and below the coil and extending around the outside of the coil and of form and material to prevent formation of eddy currents therein;

2. The combination with a melting pot having a well formed of magnetizable metal, of an electric conductor surrounding said well in the form of a coil and a return magnetic circuit formed of laminated sections in contact with the melting pot above and below the coil and extending around the outside of the coil.

In an apparatus for melting soft metal, the combination with a melting pot having a well formed of iron, a conductor for alternating electric current surrounding said well in the form of a coil, and a return magnetic circuit formed of laminated sections extending outside of the coil and contacting with the wall of the melting pot above and below said coil.

4. The combination with a melting pot for soft metal, said pot being formed of magnetizable metal and having a well of reduced diameter, of a conductor for alternating current surrounding said well in the form of a coil, and a return magnetic circuit formed of laminated sections extending outside of the coil and contacting with the melting pot above and below the coil.

5. In a melting pot for soft metal, the combination with the pot formed of iron and having a downwardly extending well of reduced diameter, a coil for the passage of alternating current, surrounding said well and a return magnetic circuit formed of laminated L-shaped sections contacting with the enlarged portion of the melting pot above the coil and with the well of the melting pot below the coil.

6. The combination with a melting pot having a pump cylinder therein both formed of magnetizable metal, a coil for alternating current surrounding the melting pot whereby magnetic conditions may be created in both the walls of the pot and pump cylinder, and a return magnetic circuit formed of laminated magnetizable metal in contact at the ends with the walls of the pot and extending around the outer side of the coil.

7. The combination with a melting pot formed of magnetizable metal with undercut brackets on its outer face, a coil for alternating current surrounding the pot below the brackets, laminated magnetizable sections seated at one end against said undercut brackets and at the opposite end against the melting pot below the coil and a removable end piece cooperating with the laminated sections for retaining them in position.

8. The combination with a melting pot having an internal cylinder, the walls of said pot and cylinder being formed of magnetizable metal and connected at top and bottom to form branches of a megnetic circuit, of a coil for alternating current surrounding the body of the melting pot and a return for the magnetic circuit extending outside of the coil and formed of sections of laminated magnetizable metal in contact with the pot above and below the coil.

9. The combination with a melting pot for metal having an internal cylinde the walls of said pot and cylinder being formed of magnetizable metal and connected at top and bottom to form branches of a magnetic circuit, said walls being spaced apart to form a chamber for the reception of the metal to be melted, said chamber surrounding one branch of the magnetic circuit, of a coil for alternating current surrounding the body of the melting pot and a return for the magnetic circuit extending outside of the coil in contact with the pot above and below the coil and of material and form to prevent the formation of eddy currents therein.

10. In a melting pot for casting machines, the combination with the melting pot body formed of magnetizable metal and a discharge duct therefor formed of magnetizable metal, of coils for the passage of alternating current surrounding the melting pot and discharge duct respectively, and magnetic circuit returns formed of laminated magnetizable metal extending around the outer sides of the respective coils.

11. The combination with a melting pot of magnetizable metal, a cylinder within the pot and a discharge duct, all of ma gnetizable metal, of a coil for alternating current surrounding the body of the melting pot, a coil for alternating current surrounding the discharge duct whereby magnetic conditions of different intensity may be established in the pot and duct respectively, and returns for the magnetic circuits extending outside of the respective coils and formed of sections of laminated magnetizable metal in contact at the ends with the magnetizable metal extending through the coils.

12. In mechanism for melting and handling molten metal, the combination with a melting pot and a discharge duct therefor formed of iron and having a discharge nozzle, of a coil for alternating current surrounding the discharge duct in proximity to the nozzle and a return for the magnetic circuit formed of a laminated metal section contacting at one end with the nozzle in front of the coil and at the opposite end with the duct in rear of the coil.

13. In mechanism for melting and handling molten metal, thecombination with a melting pot and a discharge duct therefor formed of magnetizable metal and having a discharge nozzle with flaring outer walls, of a coil for alternating current surrounding the discharge duct in proximity to the nozzle, and a return for the magnetic circuit formed of a laminated metal section contacting at its forward end with the flaring walls of the nozzle and at its rear end with the duct in rear of the coil.

14. In a heater such as described, the combination with a discharge duct of magnetizable metal having a nozzle with flaring outer walls, of a coil for alternating current surrounding the duct in rear of the nozzle and adapted to create magnetic forces therein and returns for the magnetic circuit contacting at their forward ends with the flaring walls of the nozzle and at their rear ends with the wall of the duct in rear of the coil.

15. In a heater such as described, the combination with a coil for alternating current,

a core for said coil formed of magnetizable metal with an opening therein for the sub stance to be heated and exterior brackets having inclined faces, of returns for the magnetic circuit formed of laminated metal sections having inclined faces cooperating with the inclined faces of the brackets, and means for clamping the opposite ends of the sections against the core and seating the sections against the brackets.

16. In a heater such as described, the combination with a coil for alternating current, a core of magnetizable metal extending through the coil and having an opening therein for the substance to be heated, of returns for the magnetic circuit formed of sections of laminated metal extending outside of the coil and having inclined faces at the opposite ends, and means cooperating with said inclined faces for holding the sections in position.

17. In apparatus for melting and handling molten metal, the combination with a melting pot and its discharge duct, coils for alternating current surrounding the pot and duct respectively, and returns for the magnetic circuits extending around the outer sides of the coils, of a casing for the melting pot and its duct having a seat on the rear side for the rear portion of the pot, and adjustable supports at the front cooperating with the discharge duct, whereby the melting pot, duct and heater may be adjusted in and removed from the casing.

WAYNE DOUGLAS LUDWIOK.

Witnesses:

T. J. GLovER, R. L. IVEBB.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

